i used php web proxy for limit web access in a office, clients have not internet access, so they use this php web proxy to view web page. the php proxy is running on a computer that have access to internet via a squid proxy server. ( for example i deny access to www.yahoo.com in squid ). all ok. So,if any clients send request to php proxy for yahoo.com it will be denied. ok.
But, if client open google via php proxy and search for yahoo , it shows yahoo.com at first result. then client click on result link and it will show yahoo.com website for client. how to control access in this way?